Amphoteric surfactants based upon alkyl polyglucoside

ABSTRACT

The invention relates to a series of polyglycoside derivatives that contain water-soluble groups introduced into the molecule by reaction with the hydroxyl groups present in the starting polyglycoside molecule. The preferred products have more than one water-soluble group per molecule and are made with mild reagents to avoid discoloration and mal odor. The most preferred products have between 2 and 3 functional groups per molecule. The compounds are amino functional and betaine functional alkyl polyglucoside.

FIELD OF THE INVENTION

The present invention relates to a series of polyglycoside derivatives that contain water-soluble groups introduced into the molecule by reaction with the hydroxyl groups present in the molecule. The preferred products have more than one water-soluble group per molecule and are made with mild reagents to avoid discoloration and mal odor.

Commercial alkyl polyglycosides generally have a low degree of polymerization of polysaccharide, in the molecule. This results in a molecule that is of limited water solubility. The present invention is aimed at functionalizing the hydrophobic alkyl polyglycoside, by including in the molecule amino, quaternary and betaine functional groups. These products have been called “alkyl glycosides, alkyl glycosides, alkyl polyglycosides or alkyl polyglycosides” by many different authors. All refer to the same molecules.

BACKGROUND

Alkyl polyglycosides have been known for many years, having been first synthesized in the early 1900 by Emile Fischer. Despite this, the products were of little commercial interest until much later.

U.S. Pat. No. 4,393,203 issued Jul. 12, 1983 to Mao et al, incorporated herein by reference, disclose that long chain fatty alcohols can be removed from alkyl polysaccharide products in thin film evaporators to achieve fatty alcohol levels of less than about 2% without excessive discoloration of the alkyl polysaccharide. This allowed for a more cosmetically acceptable product to be developed that is more surface active. The presence of the free fatty alcohol in the mixture, allows for a more water-soluble product, by removing the water insoluble alcohol.

One of the most significant patents is U.S. Pat. No. 5,003,057 issued Mar. 26, 1991 to McCurry et al incorporated herein by reference, provides for a process for preparing glycosides from a source of saccharide moiety and an alcohol in the presence of a hydrophobic acid catalyst is provided. An example of such a catalyst is dinonylnaphthalenemonosulfonic acid. The use of such catalysts provides a number of process advantages, which includes the reduced production of polar by-products. Preferred glycosides produced by the process are higher alkyl glycosides useful as surfactants.

U.S. Pat. No. 3,598,865 (Lew) discloses the production of higher alkyl (C.₈–C₂₅) glycosides from a monosaccharide or source thereof and a higher monohydric alcohol in the presence of a latent solvent (lower alcohols) and an acid catalyst selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, phosphorous acid, toluenesulfonic acid, and boron trifluoride.

U.S. Pat. No. 3,219,656 (Boettner) discloses a process for producing a higher alkyl glycoside by reacting glucose with methanol in the presence of a macroreticular-structured sulfonic acid resin, anhydrous and in the acid form, to produce methyl glycoside which is reacted without isolation with butanol to form butyl glycoside and which in turn is reacted with a higher alcohol to form a surface active higher alkyl glycoside.

U.S. Pat. No. 3,839,319 (Mansfield) discloses a process for producing alkyl glycosides by direct, acid catalyzed reaction of a higher alcohol and a saccharide. The acid catalysts are mineral acids such as hydrochloric and sulfuric, and sulfonic acid exchange resins.

None of the patents referenced above provide for a molecule that has the necessary water soluble group incorporated to overcome the lack of water solubility, greasy drying feel that alkyl glycosides have on the skin.

THE INVENTION

The present invention relates to the finding that the reaction of the rather hydrophobic alkyl polyglycosides with the proper reagent results in molecules that have improved water-solubility and consequently overcome many of the shortcomings of the alkyl polyglycosides itself. It is most interesting that the maximum amount of glycoside units per alkyl group that can be added using known technology is 1.5. This means that the product is a mixture of mono and di functional product. This product has the remaining fatty alcohol stripped off in an evaporative process. The resulting product is about 70% by weight of a product of a d.p. of 1, about 21% by weight of a product of a d.p. of 2, about 7% by weight of a product having a d.p. of 3, and about 2% by weight of a product that has a d.p. of 4.

We have surprisingly learned that taking the alkyl polyglycosides produced in the commercial process, with it's inherent lack of water solubility and reacting it to make anionic surface-active agents, results in a series of products that are much more usable in many applications. Simply put, alkyl polyglycosides make much better hydrophobic raw materials than finished surface-active agents. When some or all of the many hydroxyl groups are converted into amino, quaternary and betaine groups outstanding more widely applicable surface-active agents result.

The compounds of the present invention offer unappreciated advantageous over the parent alkyl poly glycoside, including increased water solubility, foam, wetting and emulsification. These properties make the compounds of the present invention very applicable to a variety of applications including personal care.

SUMMARY OF THE INVENTION

Alkyl polyglycosides are complex products made by the reaction of glucose and fatty alcohol. In dealing with the chemistry one talks about degree of polymerization (the so called “d.p.”). In the case of traditional alkyl polyglycosides the d.p. is around 1.4. This means that on average thee is 1.4 units of glucose for each alkyl group. The fact of the matter is that the resulting material is a mixture having an average of 1.4.

The specific structure of the product is hard to ascertain completely since many positional isomers are possible, but two examples of structures are as follows;

It should be clear that if there is a 50/50 mixture of the d.p. 1 and d.p. 2 product, the resulting analytical data will show that on average there is a d.p. of 1.5. Saying that a molecule has a d.p. of 1.5 does not mean that each molecule has 1.5 glucose units on it.

One key aspects of the present invention relates to the heretofore unappreciated fact that the rather hydrophobic alkyl polyglycosides contain on average five hydroxyl groups, one primary and the other four secondary. The assumption that there is a large degree of group specificity for the primary to react exclusively rather than the four additional hydroxyl groups is simply not true. This means that if on average only one of the five groups is reacted, there remains a very large concentration of reacting alkyl polyglycoside that has no functionality on it. Since the reactant with no functionalization remains water insoluble, there needs to be at lease 2 and as many as 4 hydroxyl groups functionalized to get to the desired water-soluble product. We have observed that when between 2 and 5 groups are reacted, a water-soluble very useful product results. Therefore it is a preferred embodiment having between 2 and 5 of the hydroxyl groups functionalized.

Another key unappreciated fact in making the compounds of the present invention is the selection of the proper reagents to make the desired product. Specifically, if aggressive reagents are used, the starting alkyl polyglycoside discolors and degrades quite seriously, making a large concentration of degradation products that are quite dark, smelly and not water soluble. It is a key aspect of the present invention to use a process that makes use of mild reagents, otherwise unacceptable products result. The chloro hydroxypropyl intermediates are key to the preparation of the compounds of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The compositions of the present invention are mixtures conform to the following structures:

-   wherein; -   R is alkyl having 8 to 22 carbon atoms; -   R¹, R², R³, and R⁴ are independently selected from the group     consisting of:     —CH₂—CH(OH)—CH₂—N—(CH₂CH₂OH)₂     and     -   and H, with the proviso that R¹, R², R³, and R⁴ are not all H;         and -   wherein; -   R is alkyl having 8 to 22 carbon atoms; -   R⁵, R⁶, R⁷, R⁸; R⁹, R¹⁰ and R¹¹ are independently selected from the     group consisting of     —CH₂—CH(OH)—CH₂—N—(CH₂CH₂OH)₂     and     -   and H, with the proviso that are R⁵, R⁶, R⁷, R⁸; R⁹, R¹⁰ and R¹¹         not all H.

PREFERRED EMBODIMENT

In a preferred embodiment R⁵, R⁶, R⁷, R⁸; R⁹ and R¹⁰ are independently selected from H and —CH₂—CH(OH)—CH₂—N—(CH₂CH₂OH)₂ with the proviso that R⁵, R⁶, R⁷, R⁸, R⁹ R¹⁰ and R¹¹ are not all H.

In a preferred embodiment R⁵, R⁶, R⁷, R⁸; R⁹ and R¹⁰ are independently selected from H and

-   -   with the proviso that R⁵, R⁶, R⁷, R⁸, R⁹ R¹⁰ and R¹¹ are not all         H.

In a preferred embodiment R is alkyl having 8 to 22 carbon atoms.

EXAMPLES Preparation of alkyl Glycosides

Alkyl Glycosides are raw materials used to make the surface-active polyglycoside derivatives of the present invention.

Saccharides useful in the process of making alkyl glycosides are saccharides that can be alkylated in the “1” position, commonly referred to as “reducing saccharides”, or higher saccharides that can be hydrolyzed to provide such a saccharide. These saccharides are typically comprised of aldo- or keto-hexoses or pentoses.

Examples of saccharides include glucose (dextrose), fructose, mannose, galactose, talose, allose, altrose, idose, arabinose, xylose, lyxose, and ribose. Examples of hydrolyzable saccharides that are a source of reducing saccharides include starch, maltose, sucrose, lactose, maltotriose, xylobiose, mellibiose, cellobiose, raffinose, stachiose, methyl glycosides, butyl glycosides, levoglucosan, and 1,6-anhydroglucofuranose.

The physical form of the saccharide may vary. The saccharide will typically be in a fluid (as opposed to a solid) state, e.g. as a melt or an aqueous syrup, during at least a portion of the period of reaction, if not for a predominant portion of the period of the reaction. Crystalline (e.g. anhydrous or hydrates) or amorphous saccharide solids in various particle sizes, e.g. granules, powders, etc., can be used, but the heating of the reaction medium may well fluidize at least a portion of a solid reactant, if not a predominant portion of the saccharide reactant. Aqueous syrups of saccharides, typically at saccharide solids of between about 10% and 90% dry solids by weight can also be used. Indeed, the use of the hydrophobic catalysts of this invention should show the most improved results over conventional catalysts in the context of the use of aqueous syrup reactants as compared with processes which employ solid saccharide reactants, particularly with respect to avoiding the formation of deleterious amounts of polysaccharides and very high DP alkyl glycosides during the glycoside formation reaction.

The preferred saccharides are glucose, galactose, xylose and arabinose, or mixtures thereof, for reasons of availability, low cost, and convenience. Glucose in the anhydrous crystalline form is preferred, although dextrose monohydrate, corn syrups of high dry solids (typically 50% to 80% dry solids) and a high dextrose equivalence (D.E.) (typically greater than 90 D.E and most commonly 95 D.E.) can be commonly employed. Indeed, while the higher the purity of the dextrose source, the better the quality of the product (other things being equal), the catalysts of this invention allow the use of a lower purity dextrose source and yet yield a product of substantially equivalent quality as compared with prior catalysts. Because of the ready availability of glucose and its oligomers, much of the remaining description is particularly suited to the use of glucose in its various forms.

Alcohols useful in the process of this invention are hydroxyl-functional organic compounds capable of alkylating a saccharide in the “I” position. The alcohol can be naturally occurring, synthetic, or derived from natural sources and/or derivatized. Examples include monohydric alcohols (more fully discussed below) and polyhydric alcohols (e.g. ethylene glycol, propylene glycol, polyethylene glycols, polypropylene glycols, butylene glycol, glycerol, trimethylolpropane, pentaerythritol, polyester polyols, polyisocyanate polyols, and so on). Other examples include aromatic alcohols such as benzyl alcohol, phenol, substituted phenols (e.g. alkylphenols) and alkoxylates of each.

Preferred alcohols are monohydric alcohols containing from about 1 to about 30 carbon atoms. They may be primary or secondary alcohols, straight or branched chain, saturated or unsaturated (e.g. allyl alcohol, 2-ethylhexenyl alcohol and oleyl alcohol) alkyl or aralkyl alcohols, ether alcohols, cyclic alcohols, or heterocyclic alcohols. In general, these alcohols have minimal solvent power for the saccharide molecule. Examples of the monohydric alcohols which may be employed in the present invention include methyl alcohol, isopropyl alcohol, butyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, pentadecyl alcohol, hexadecyl alcohol, pentacosyl alcohol, oleyl alcohol, linoleyl alcohol, isoborneol alcohol, hydroabietyl alcohol, phenoxyethanol, phenoxypolyethoxyethanol containing five ethoxy groups, 2-methyl-7-ethyl-4-undecanol, and mixtures of one or more of the above.

A preferred group of alcohols are alkanols having the formula ROH wherein R represents an alkyl group having from 8 to 30 carbon atoms. A particularly preferred group of alcohols are those wherein R represents an alkyl radical having from 8 to 20, preferably II to 18, carbon atoms. The alkyls can be straight or branched chain.

Alkyl Glycoside Examples Example 1

A one-liter, four-necked, round-bottomed flask was equipped through its center neck with an overhead mechanical stirrer, through a second neck with a distillation head fitted with an addition funnel and a condenser/receiver/vacuum take-off assembly, through a third neck fitted with a three hole rubber stopper with a capillary nitrogen bleed, a calibrated mercury thermometer and a vacuum tight temperature controller probe, and on the fourth neck with a septum for sampling.

The flask was charged with 602.4 g (3.105 moles) of a commercial mixture of C₁₁ to C₁₅ (98% C₁₂ and C₁₃) straight and branched alkanols (Neodol 23 available form Shell Chemical Co.) and 136.6 g (0.69 moles) of a commercially available dextrose monohydrate (Staleydex 333, available from A. E. Staley Mfg. Co. at 9.0% moisture). The slurry was heated at a vacuum of 30 mm Hg (absolute). Water was released starting at about 57.degree. C. and heating was continued until the slurry had reached 110.degree. C. At this time 3.2 g (0.00345 mole of a commercially available mixture of 50% dinonylnaphthalenesulfonic acid in heptane (available from King Industries) was added as a catalyst and the theoretical volume of water distilled at about a linear rate over 8 hours. After stirring an additional hour, a stoichiometric amount of aqueous NaOH (33% in H₂O) was added. An aliquot of the neutralized reaction mixture (3.39 g, 1 g dissolved substance) was dissolved in a total volume of 10 ml with 1:1 isopropanol:water. The pH of this solution was 7.8.

The remainder of the reaction mixture was evaporated to a clear melt at 200° C. and 1 mm pressure using a Leybold-Heraeus Distact.™. wiped film evaporator operating at a feed rate of 700 ml/hr.

The residue was analyzed using a combination of gas and liquid chromatographic techniques as well as NMR spectroscopy and was shown to contain less than 0.2% free alcohol and less than 2% polar species (HPLC) and an NMR mole ratio of glucose rings to fatty chains of about 1.4.

Example 2–8

The same one-liter, four-necked, round-bottomed flask was equipped through its center neck with an overhead mechanical stirrer, through a second neck with a distillation head fitted with an addition funnel and a condenser/receiver/vacuum take-off assembly, through a third neck fitted with a three hole rubber stopper with a capillary nitrogen bleed, a calibrated mercury thermometer and a vacuum tight temperature controller probe, and on the fourth neck with a septum for sampling.

The flask was charged with 3.105 moles of the specified alcohol and 136.6 g (0.69 moles) of a commercially available dextrose monohydrate (Staleydex 333, available from A. E. Staley Mfg. Co. at 9.0% moisture). The slurry was heated at a vacuum of 30 mm Hg (absolute). Water was released starting at about 57.degree. C. and heating was continued until the slurry had reached 110.degree. C. At this time 3.2 g (0.00345 mole of a commercially available mixture of 50% dinonylnaphthalenesulfonic acid in heptane (available from King Industries) was added as a catalyst and the theoretical volume of water distilled at about a linear rate over 8 hours. After stirring an additional hour, a stoichiometric amount of aqueous NaOH (33% in H₂O) was added. An aliquot of the neutralized reaction mixture (3.39 g, 1 g dissolved substance) was dissolved in a total volume of 10 ml with 1:1 isopropanol:water. The pH of this solution was 7.8.

The remainder of the reaction mixture was evaporated to a clear melt at 200° C. and 1 mm pressure using a Leybold-Heraeus Distact.™. wiped film evaporator operating at a feed rate of 700 ml/hr.

The residue was analyzed using a combination of gas and liquid chromatographic techniques as well as NMR spectroscopy and was shown to contain less than 0.2% free alcohol and less than 2% polar species (HPLC) and an NMR mole ratio of glucose rings to fatty chains of about 1.4. The hydroxyl value was run on the resultant product and is indicated below.

Example Alkyl OH Value 2 C12H25 691.9 3 C10H21 741.8 4 C8H17 795.4 5 C14H27 653.8 6 C18H37 584.4 7 C18H35 586.7 8 C20H42 555.1 9 C22H42 531.2

Alkyl Polyglucoside Surfactants

There are a number of water-soluble groups that can be introduced into the finished alkyl polyglycoside. These include they are all introduced by making an intermediate amino compound.

It will be clearly understood that the alkyl polyglycosides of the present invention have a number of hydroxyl groups present in the molecule. The number of hydroxyl groups functionalized will have a profound effect upon the degree of increased water solubility of the molecule.

The present invention includes a functionalization of a low number of hydroxyl groups (one per molecule) to a high number (all groups on the molecule). The preferred number to functionalize is an intermediate number of groups (approximately half of the number present).

Alkyl Polyglucoside Amine

The reaction to make the amino compound of the present invention is conducted using the following intermediate: Cl—CH₂—CH(OH)CH₂—N—(CH₂CH₂OH)₂ This intermediate is available from Siltech LLC Dacula, Ga.

Example 9

Cl—CH₂—CH(OH)CH₂—N—(CH₂CH₂OH)₂

It will be clearly understood that the alkyl polyglycoside has on average five hydroxyl groups when the d.p. is 1.4. The phosphation can include all five, but in a more preferred embodiment includes between one and three hydroxyl groups. This ratio provides the best degree of water solubility. The most preferred number of hydroxyl groups to amine is 2.

The reaction sequence is as follows:

General Procedure

General Procedure—To a flask equipped with agitation, heat, thermometer and nitrogen sparge is added the specified amount of the specified alkyl polyglucoside and enough water to make the final product have a solids of 35% by weight. The alkyl polyglucoside is heated to melt. Next, add the specified number of grams of chloro reactant Example 9 is added under good agitation and nitrogen sparge. Next is added 0.5% sodium methylate. The % is by weight and is based upon the total amount of all materials reacted. Nitrogen sparge is simply nitrogen bubbled through the liquid contents of the flask. This keeps the color light, minimizing oxidation and color formation. The reaction mass is heated to 90–100° C., and is held for 5–8 hours. Testing for the concentration of Chloride ion follows the reaction progress. Once the theoretical value is reached, the reaction is terminated and the product is used without additional purification.

Example 10–16 Alkyl Polyglucoside Example 9

Example Example Grams Grams OH Groups Reacted 10 1 446 194.0 1 11 2 416 194.0 1 12 3 388 388.0 2 13 4 472 582.0 3 14 5 528 776.0 4 15 6 526 388.0 2 16 7 556 776.0 4 17 8 581 388.0 2

Preparation of the Betaine Example 18–25

The reaction sequence is as follows:

General Procedure

To a flask equipped with agitation, heat, thermometer and nitrogen sparge is added the entire product of examples for the amino alkyl polyglucoside having a solids of 35% by weight (examples 10–17). The solution is heated to melt. Next, add the specified number of grams of sodium chloro acetate is added under good agitation and nitrogen sparge. Nitrogen sparge is simply nitrogen bubbled through the liquid contents of the flask. This keeps the color light, minimizing oxidation and color formation. The reaction mass is heated to 90–100° C., and is held for 5–8 hours. Testing for the concentration of chloride ion follows the reaction progress. Once the theoretical value is reached, the reaction is terminated and the product is used without additional purification.

Sodium Chloroacetate

Example Example Grams OH Groups Reacted 18 10 38.0 1 19 11 38.0 1 20 12 76.0 2 21 13 114.0 3 22 14 266.0 5 23 15 76.0 2 24 16 190.0 4 25 17 76.0 2

Applications Examples

The compounds of the present invention are water soluble high foaming surfactants that are mild to the skin and have outstanding color and odor. They are outstanding wetting agents.

They are particularly suited for use in personal care applications like bubble bath, shampoos and body wash. They are also very good additives for hard surface cleaners and detergent systems.

While the illustrative embodiments of the invention have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and descriptions set forth hereinabove but rather that the claims be construed as encompassing all the features of patentable novelty which reside in the present invention, including all features which would be treated as equivalents thereof by those skilled in the art to which the invention pertains. 

1. A surfactant composition which comprises a mixture of compounds conforming to the following structures:

wherein; R is alkyl having 8 to 22 carbon atoms; R¹, R², R³, and R⁴ are independently selected from the group consisting of —CH₂—CH(OH)—CH₂—N—(CH₂CH₂OH)₂

 and H, with the proviso that R¹, R², R³, and R⁴ are not all H; and

wherein; R is alkyl having 8 to 22 carbon atoms; R⁵, R⁶, R⁷, R⁸; R⁹, R¹⁰ and R¹¹ are independently selected from the group consisting of —CH₂—CH(OH)—CH₂—N—(CH₂CH₂OH)₂

 and H, with the proviso that R⁵, R⁶, R⁷, R⁸, R⁹ R¹⁰ and R¹¹ are not all H.
 2. A surfactant composition of claim 1 wherein; R¹, R², R³, and R⁴ are independently selected from the group consisting of —CH₂—CH(OH)—CH₂—N—(CH₂CH₂OH)₂  and H, with the proviso that R¹, R², R³, and R⁴ are not all H; and R⁵, R⁶, R⁷, R⁸; R⁹, R¹⁰ and R¹¹ are independently selected from the group consisting of —CH₂—CH(OH)—CH₂—N—(CH₂CH₂OH)₂  and H, with the proviso that R⁵, R⁶, R⁷, R⁸, R⁹ R¹⁰ and R¹¹ are not all H.
 3. A surfactant composition of claim 1 wherein R¹, R², R³, and R⁴ are independently selected from the group consisting of

 and H, with the proviso that R¹, R², R³, and R⁴ are not all H; and R⁵, R⁶, R⁷, R⁸; R⁹, R¹⁰ and R¹¹ are independently selected from the group consisting of

 and H, with the proviso that R⁵, R⁶, R⁷, R⁸, R⁹ R¹⁰ and R¹¹ are not all H.
 4. A surfactant composition of claim 2 wherein R is C₁₂H₂₅.
 5. A surfactant composition of claim 2 wherein R is C₁₀H₂₁.
 6. A surfactant compositions of claim 2 wherein R is C₂₂H₄₂.
 7. A surfactant compositions of claim 3 wherein R is C₁₂H₂₅.
 8. A surfactant compositions of claim 3 wherein R is C₁₀H₂₁.
 9. A surfactant composition of claim 3 wherein R is C₂₂H₄₂. 